1. Agropyron cristatum (L.) Gaertn. (standard wheatgrass, crested wheatgrass)

Pl. 186 c, d; Map 745

Plants perennial, forming tufts or clumps. Flowering stems 25–70(–100) cm long, erect or ascending, glabrous. Leaf sheaths glabrous or the lowermost hairy, the ligule short, membranous. Leaf blades 2–20 cm long, 2–7 mm wide, usually flat, often with a pair of auricles at the base, glabrous or roughened to hairy on the upper surface. Inflorescences 2–8 cm long, ovate to lanceolate in outline, somewhat flattened, with numerous densely spaced, spreading to loosely ascending spikelets crowded along the axis, the internodes 0.5–2.5 mm long near the middle of the inflorescence. Spikelets single at the nodes of the inflorescence, all similar in size and appearance, 7–10 mm long, linear in outline, with 3–7 florets, disarticulating above the glumes. Glumes 3–6 mm long, 0.5–2.0 mm wide, narrowly lanceolate, the tip tapered to a narrow point or an awn 0.5–3.0 mm long, 1‑ or 3‑nerved, glabrous or roughened. Lemmas 4–7 mm long, elliptic‑lanceolate, the tip pointed or with an awn 1–5 mm long, 1‑ or 3‑nerved, usually somewhat keeled, usually glabrous, lacking stiff, spinelike hairs along the keel and margins. Anthers 2.5–4.0 mm long. Fruits 3–4 mm long, linear, brown. 2n=14, 28, 42. May–June.

Introduced, uncommon in Franklin County and St. Louis (native of Europe and Asia, widely planted as a forage grass in the U.S., widely escaped, but seldom naturalized). Pastures, railroads.

Crested wheatgrass is an important pasture grass in portions of the western and northern United States and Canada. Within its native range, Agropyron is generally treated as containing six or more closely related species. The original report for Missouri was of A. desertorum (Fischer ex Link) Schultes, which is said to differ from true A. cristatum in its longer inflorescence with more strongly ascending spikelets and its slightly shorter spikelets. However, the numerous cultivars released for agricultural purposes in the United States do not lend themselves readily to determination using keys for wild material. Thus, most authors of American floristic manuals (Sutherland, 1986; Gleason and Cronquist, 1991) continue to treat the A. cristatum complex as containing a single, polymorphic species.